Initial commit
diff --git a/examples/task-id.rs b/examples/task-id.rs
new file mode 100644
index 0000000..b3832d0
--- /dev/null
+++ b/examples/task-id.rs
@@ -0,0 +1,88 @@
+//! An executor that assigns an ID to every spawned task.
+
+#![feature(async_await)]
+
+use std::cell::Cell;
+use std::future::Future;
+use std::panic::catch_unwind;
+use std::thread;
+
+use crossbeam::atomic::AtomicCell;
+use crossbeam::channel::{unbounded, Sender};
+use futures::executor;
+use lazy_static::lazy_static;
+
+#[derive(Clone, Copy, Debug)]
+struct TaskId(usize);
+
+thread_local! {
+ /// The ID of the current task.
+ static TASK_ID: Cell<Option<TaskId>> = Cell::new(None);
+}
+
+/// Returns the ID of the currently executing task.
+///
+/// Returns `None` if called outside the runtime.
+fn task_id() -> Option<TaskId> {
+ TASK_ID.with(|id| id.get())
+}
+
+/// Spawns a future on the executor.
+fn spawn<F, R>(future: F) -> async_task::JoinHandle<R, TaskId>
+where
+ F: Future<Output = R> + Send + 'static,
+ R: Send + 'static,
+{
+ lazy_static! {
+ // A channel that holds scheduled tasks.
+ static ref QUEUE: Sender<async_task::Task<TaskId>> = {
+ let (sender, receiver) = unbounded::<async_task::Task<TaskId>>();
+
+ // Start the executor thread.
+ thread::spawn(|| {
+ TASK_ID.with(|id| {
+ for task in receiver {
+ // Store the task ID into the thread-local before running.
+ id.set(Some(*task.tag()));
+
+ // Ignore panics for simplicity.
+ let _ignore_panic = catch_unwind(|| task.run());
+ }
+ })
+ });
+
+ sender
+ };
+
+ // A counter that assigns IDs to spawned tasks.
+ static ref COUNTER: AtomicCell<usize> = AtomicCell::new(0);
+ }
+
+ // Reserve an ID for the new task.
+ let id = TaskId(COUNTER.fetch_add(1));
+
+ // Create a task that is scheduled by sending itself into the channel.
+ let schedule = |task| QUEUE.send(task).unwrap();
+ let (task, handle) = async_task::spawn(future, schedule, id);
+
+ // Schedule the task by sending it into the channel.
+ task.schedule();
+
+ handle
+}
+
+fn main() {
+ let mut handles = vec![];
+
+ // Spawn a bunch of tasks.
+ for _ in 0..10 {
+ handles.push(spawn(async move {
+ println!("Hello from task with {:?}", task_id());
+ }));
+ }
+
+ // Wait for the tasks to finish.
+ for handle in handles {
+ executor::block_on(handle);
+ }
+}